A manufacturer is designing a product layout for a new product production. plans to use a production line for 8 hours per day in order to meet forecasted demand of 70 units per day. The product requires 7 tasks in total. These tasks are namely, A, B, C, D, E, F, and G respectively. Task A does not have any predecessor to start. To start Task B, it requires Task A to be completed. Starting tasks C needs, the task B to be completed. Also, starting task D needed task B to be completed. Task E can only start upon completion of Task C. Whereas starting task F needs the completion of both the tasks D and E. Finally, starting task G needed, task F to be completed. The processing times for tasks, A, B, C, D, E, F, and G are 2.8, 2.1, 0.9, 1.0, 1.2, 1.8, are 4.7 :minutes respectively. How many minimum numbers of workstations are needed?